Apparatus, systems, and methods for optical channel management

ABSTRACT

An apparatus includes a reconfigurable optical add/drop multiplexer (ROADM) having an input port to receive a first optical signal from a second device. The ROADM also includes a first wavelength selective switch (WSS), in optical communication with the input port, to convert the first optical signal into a second optical signal, a loopback, in optical communication with the first WSS, to transmit the second optical signal, and a second WSS, in optical communication with the loopback, to convert the second optical signal to a third optical signal and direct the third optical signal back to the second device via the input port.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.16/836,102, now U.S. Pat. No. 11,044,035, filed Mar. 31, 2020, entitled“Apparatus, Systems, and Methods for Optical Channel Management”, whichis a continuation of U.S. patent application Ser. No. 15/639,247, nowU.S. Pat. No. 10,615,901, filed Jun. 30, 2017, and entitled “Apparatus,Systems, and Methods for Optical Channel Management”, the disclosure ofwhich is incorporated herein by reference in its entirety.

FIELD

One or more embodiments relate to apparatus, systems, and methods ofoptical channel management.

BACKGROUND

In some instances, it may be important for a network administrator todetermine the topology an optical network. For example, it may behelpful for the network administrator to determine that an optical fiberconnects a given port of one device in the optical network to a givenport of another device in the optical network. Knowledge of the topologyof the optical network may be helpful when establishing routes throughthe optical network, diagnosing and remedying problems in the opticalnetwork, and performing other manual or automated network managementtasks.

For example, an optical network may include a router, amultiplexer/demultiplexer (Mux/Demux), and a reconfigurable opticaladd-drop multiplexer (ROADM). The connections of these devices caninvolve about 400 touch points for 100 different wavelengths. In knownoptical networks, the access link is manually provisioned. In addition,in case of misconnection or misconfiguration, usually no mechanismexists to identify the root cause. Moreover, routers and ROADMstypically use different command line interface (CLI) dialects, therebyrendering the correlation of relevant information challenging.

Another approach to determine the topologies of optical networks uses adevice sending wavelength-modulated optical signals on various ports ofthe device. The wavelength-modulated optical signal sent on a given portof the sending device is encoded with identification informationspecific to the given port. If a device receives the modulated opticalsignal on a given port, the receiving device demodulates the opticalsignal and outputs a report message to a network management system(NMS). The report message indicates the source of the received signal.The NMS may use such messages to generate topology data for the opticalnetwork. A problem with this approach is that the receiving deviceincludes hardware to demodulate the optical signal and such hardware maybe complex and expensive, thereby increasing the cost of the resultingoptical network.

SUMMARY

Some embodiments described herein relate generally to optical channelmanagement, and, in particular, to optical channel management usingreconfigurable optical add/drop multiplexers (ROADM) with loopbackfunctions.

In some embodiments, an apparatus includes a reconfigurable opticaladd/drop multiplexer (ROADM) having an input port to receive a firstoptical signal from a second device. The ROADM also includes (1) a firstwavelength selective switch (WSS), in optical communication with theinput port, to convert the first optical signal into a second opticalsignal; (2) a loopback, in optical communication with the first WSS, totransmit the second optical signal; and (3) a second WSS, in opticalcommunication with the loopback, to convert the second optical signal toa third optical signal and direct the third optical signal back to thesecond device via the input port.

In some embodiments, a method includes receiving a first optical signalfrom a second device via an input port of a reconfigurable opticaladd/drop multiplexer (ROADM). The method also includes transmitting thefirst optical signal to a first wavelength selective switch (WSS) toconvert the first optical signal into a second optical signal andtransmitting the second optical signal to a second WSS, in opticalcommunication with the input port, to convert the second optical signalto a third optical signal. The method also includes transmitting thethird optical signal towards the second device via the input port.

In some embodiments, a reconfigurable optical add/drop multiplexer(ROADM) includes an input port to receive a first optical signal from asecond device and a first wavelength selective switch (WSS), in opticalcommunication with the input port, to convert the first optical signalinto a second optical signal. The ROADM also includes a first spectralanalyzer, operatively coupled to the input port, to acquire firstspectral information of the first optical signal. An opticaltransmission line is in optical communication with the first WSS totransmit the second optical signal towards the second device. The ROADMalso includes at least one user port, operatively coupled to the firstWSS, to receive at least a portion of the second optical signal. Asecond spectral analyzer is operatively coupled to the at least one userport to acquire second spectral information of the second opticalsignal. The ROADM further includes an optical channel monitor (OCM)operatively coupled to the first spectral analyzer and the secondspectral analyzer. The OCM is configured to receive the first spectralinformation so as to locate the at least one user port, receive thesecond spectral information from the second spectral analyzer, andtransmit the second spectral information to the second device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic of an apparatus with loopback capability foroptical channel management, according to some embodiments.

FIG. 2 shows a schematic of a wavelength selective switch (WSS) that canbe used in the apparatus shown in FIG. 1, according to embodiments.

FIG. 3A shows a schematic of an optical network using a fixed-colorMux/Demux and the apparatus shown in FIG. 1 for optical channelmanagement, according to embodiments.

FIG. 3B shows a schematic of an optical network using a colorlessMux/Demux and the apparatus shown in FIG. 1 for optical channelmanagement, according to embodiments.

FIG. 4 illustrates a method of optical channel management using areconfigurable optical add/drop multiplexer (ROADM) with loopbackcapability, according to embodiments.

FIGS. 5A and 5B illustrate flowchart for a method of optical channelconsistency test performed on a router, according to embodiments.

FIG. 6 illustrates flowchart for a method of optical channel consistencytest steps performed on a ROADM, according to embodiments.

FIG. 7 illustrates a flowchart for a method of optical channel sweeptest performed on a router, according to embodiments.

FIG. 8 illustrates a flowchart for a method of optical channel sweeptest performed on a ROADM, according to embodiments.

FIG. 9 illustrates a flowchart for a method of optical channel discoveryperformed on a router, according to embodiments.

FIG. 10 illustrates a flowchart for a method of optical channeldiscovery steps performed on a ROADM in, according to embodiments.

DETAILED DESCRIPTION

In some embodiments, an apparatus includes a reconfigurable opticaladd/drop multiplexer (ROADM), which in turn includes (1) an input portto receive a first optical signal from a second device and (2) a firstwavelength selective switch (WSS), in optical communication with theinput port, to convert the first optical signal into a second opticalsignal. A loopback is included in the ROADM and in optical communicationwith the first WSS to transmit the second optical signal to a secondWSS. The second WSS converts the second optical signal to a thirdoptical signal and directs the third optical signal back to the seconddevice via the input port.

In some embodiments, the ROADM is implemented in an optical networkincluding a router and a Mux/Demux to receive optical signals from therouter via the Mux/Demux. The ROADM is also configured to transmitoptical signals to the router via the Mux/Demux. The loopback in theROADM allows a test of the optical path between the router and the ROADMin both directions prior to putting the link into service. This can beuseful for the execution of a discovery method. Typical state-of-the-artROADMs only passively pass through optical signals and measure theirpower, without the ability to actively transmit light. With theloopback, the ROADM disclosed herein transmit a portion of the receivedlight back to the router to complete the discovery process and measurethe quality.

In addition, known methods in optical channel management may discoverthe transmitter-ROADM direction, assuming that the reverse direction(i.e. ROADM-transmitter direction) would work. As a result, a receivedoptical signal having a bad quality may be caused by a bad patch cablemiles away from the location of installation. Upon introducing theloopback capability into the discovery phase, a quality test can beimplemented to ensure that after a successful discovery, the locationwhere transmitter (e.g., on the router) and ROADM are connected isoperational. The same procedure can be implemented at the remote end,after which wavelengths can be set up automatically with high confidenceabout the optical signal quality.

FIG. 1 shows a schematic of an apparatus 100 for optical channelmanagement according to an embodiment. The apparatus 100 is usuallyconfigured as a ROADM and includes a two input ports 110 a and 110 b toreceive an input signal (referred to as a first optical signal) fromanother device (also referred to herein as a “second device”), such as arouter or a Mux/Demux (see, e.g., FIG. 3). Using the input port 110 a asan example, the input signal received by this input port 110 a istransmitted to a first wavelength selective switch (WSS) 120 a togenerate a second optical signal. A loopback 130 is in opticalcommunication with the first WSS 120 a to receive the second opticalsignal and sends (or loopbacks) the second optical signal to a secondWSS 120 b. The transmission through the second WSS 120 b generates athird optical signal and directs the third optical signal back to thesecond device via the input port 110 a. The third optical signal can beused for optical channel management, such as channel discovery andchannel provisioning.

As used herein, the terms “first,” “second,” and “third” are used todenote differences in the respective signal. The differences may includethe location of the respective signal. For example, the second opticalsignal refers to the optical signal after the first WSS 120 a, and thethird optical signal refers to the optical signal after the second WSS120 b. The differences may also include the order in which these signalsare discussed and/or recited in the claims. In addition, the term“generates” as used herein includes the action of redirection,amplification, and/or transmission. For example, the second opticalsignal can be generated via the transmission of the first optical signalthrough the first WSS 120 a, and the third optical signal can begenerated via the transmission of the second optical signal through thesecond WSS 120 b. Accordingly, in some implementations, the firstoptical signal can be substantially identical to the second opticalsignal. In some implementations, the third optical signal can besubstantially identical to the second optical signal. In someimplementations, the third optical signal can be the second opticalsignal after amplification.

Similarly, the second input port 110 b can also receive an input signaland transmit the input signal through the first WSS 120 a, the loopback130, and the second WSS 120 b. The optical signal after the second WSS120 b is directed back to the second input port 110 b, which transmitsthe optical signal back to the second device.

FIG. 1 shows two input ports 110 a and 110 b in the apparatus 100 forillustrative purposes. In practice, the apparatus 100 can include anyother number of input ports (e.g., 3 input ports, 5 input ports, 10input ports, or more, including any values and sub ranges in between).Similarly, the apparatus 100 can also include any other number of WSS(e.g., 3 WSS, 5 WSS, 10 WSS, or more, including any values and subranges in between). In some embodiments, the two input ports 110 a and110 b share the same pair of WSS 120 a and 120 b, as shown in FIG. 1. Insome other embodiments, each of the input ports can have its own pair ofWSSs.

In some implementations, the loopback 130 includes an optical waveguide,such as a fiber or a semiconductor waveguide. As shown in FIG. 1, theloopback 130 further includes an amplifier 135 to amplify the secondoptical signal so as to increase the signal amplitude transmitted backto the second device. For example, the amplifier 135 can include anerbium-doped fiber amplifier for optical amplification.

The apparatus 100 also includes two spectral analyzers 155 a and 155 b(collectively referred to as spectral analyzers 155) to facilitateestimation of spectral information of input signals received by thefirst input port 110 a and the second input port 110 b, respectively.The spectral analyzers 155 are also referred to as fiber tap-off,couplers, or splitters, and they couple a portion of the input signalsto an optical channel monitor (OCM) 150 via an optical switch 140. TheOCM 150 can estimate the spectral information (e.g., wavelength and/orspectral density) of the input signals.

Part of the second optical signal (also referred to as drop signal)generated by the first WSS 120 a is transmitted to a user port 160 a.The apparatus 100 also includes a second user port 160 b, whereinformation about the summary of wavelength is transmitted to a fiber orreceived from a fiber. FIG. 1 shows that a fiber pair is connected tothe port 160 b, where the upper one can be a receiving fiber and thelower one can be a transmitting fiber.

A third spectral analyzer 155 c is disposed within the beam path of thesecond optical signal to couple a portion of the second optical signalto the OCM 150 for spectral analysis. The user port 160 a is alsoconfigured to add optical signals (also referred to as “add signals”)back to the second device. In this case, a fourth spectral analyzer 155d is disposed within the beam path to couple a portion of the addsignals to the OCM 150 for spectral analysis. In addition, part of theadd signals and drop signals are transmitted to a monitoring port 170.Two additional spectral analyzers 155 e and 155 f are employed to splitpart of the add signals and the drop signals (after a pre-amplifier anda post-amplifier, respectively) to the OCM 150 for spectral analysis.

The spectral information acquired or identified by the OCM 150 can beused for several functions. In one implementation, the apparatus 100includes multiple user ports 160, each of which is configured to deliveroptical signals having a distinct wavelength. Based on the spectralinformation of the second optical signal, the OCT 150 can determine thelocation of the user port that receives the second optical signal (i.e.location of the user port).

In some other implementations, the apparatus 100 includes multiple userports 160, where one of them is configured to receive the second opticalsignal and the remaining users ports 160 do not receive the secondsignal. Each user port 160 is coupled to a respective spectral analyzer155 to facilitate estimation of spectral information of possible signalsthat may be transmitted to the given user port 160. The OCM 150 in thiscase can first estimate the signal power of the possible signals to eachuser port 160. In the event that one user port 160 has a signal powergreater than a threshold value, the OCM 150 then estimates the spectralinformation of the signals that are transmitted to that user port andlocate the user port based on the spectral information. This approachmay reduce the power consumption for computation because it typicallytakes less computation power to estimate the signal powers than toestimate the signal spectrum.

In some embodiments, part or all of the spectral information acquired oridentified by the OCM 150 is transmitted back to the second device(e.g., a router). Based on the received spectral information, the seconddevice can determine whether the second device is correctly coupled tothe apparatus.

FIG. 2 shows a schematic of a WSS 200 that can be used in the ROADM 100shown in FIG. 1. The WSS 200 includes an input port 210 to receive aninput signal (e.g., from an input fiber) and split the input signal intomultiple spectral components 220, each of which has a distinctwavelength (or a distinct spectral component). Each spectral component220 is received by a corresponding optical switch 230, which can directthe given spectral component 220 to any of the output ports 240. Eachoutput port 240 can be coupled to a corresponding output fiber todeliver the spectral component.

In some implementations, the WSS 200 can employ Micro Electro MechanicalSystems (MEMS) technologies to constructs movable micro-mirrors (i.e.,the optical switches 230) that can deflect optical signals from input tooutput fibers. As far as medium- and large-size switching fabrics areconcerned, micro-mirrors can be arranged into two-dimensional orthree-dimensional arrays.

In some implementations, the WSS 200 can use liquid crystal to constructthe optical switches 230. For example, in a 1×2 optical switch, apolarizing beam splitter can be used to divide input signals into twopolarization components, which are then directed to two active cellsfilled with liquid crystals. Depending on whether a driving voltage isapplied or not, the active cells either change the polarization statesof the incident beams or leave them unaltered. A beam combiner can beused to direct the beam to the desired output port. These switches arewavelength selective, i.e. they can switch signals depending on theirwavelength. This is a very attractive feature as it allows adding anddropping single wavelengths from a multi-wavelength beam, without theneed of electronically processing the whole signal.

In some implementations, the WSS 200 can be based on the thermo-opticeffect. Two categories of thermo-optic switches include interferometricand digital optical switches. In some embodiments, the WSS 200 usesinterferometric switches, which are usually based on Mach-Zenderinterferometers. These switches 230 can include a first coupler thatsplits the input signal into two beams, which then travel through twodistinct arms having the same length. A second coupler merges orcombines the two signals from the two arms and splits the signal again.Heating one arm of the interferometer causes its refractive index tochange, thereby producing a variation of the optical path of that armand accordingly a phase difference between the two signals propagatingin the two arms. As interference of the two signals alternate betweenconstructive interference and destructive interference, the power onalternate outputs can be minimized or maximized, thereby selecting theoutput port.

In some implementations, the WSS 200 can use digital optical switches,which are integrated optical devices made of silica on silicon. Thedigital optical switch includes two interacting waveguide arms throughwhich light propagates. The phase error between the beams at the twoarms can determine the output port. Heating one of the arms changes itsrefractive index, and the light is transmitted down one path rather thanthe other.

In some implementations, the WSS 200 use electro-holography, which is abeam-deflection method based on controlling the reconstruction processof volume holograms by means of an electric field. Holograms are storedas a spatial distribution of charge in crystals. The application of adriving voltage is used to activate pre-stored holograms in order todeflect properly light beams. In both states of the switch, the outputbeams are diffracted beams. If there is no voltage applied, the crystalis transparent to optical signals and pass the optical signals. If asuitable driving voltage is applied, the optical signals crossing thecrystal are deflected. As it is possible to store several holograms inthe same crystal, these devices can be used to drop even singlewavelengths, or groups of wavelengths, from a WDM signal.

FIG. 3 FIG. 3A shows a schematic of an optical network 301 including afixed-color Mux/Demux 321 and a ROADM 331. The ROADM 331 can be, forexample, similar to the ROADM discussed above in reference to FIG. 1.The Mux/Demux 321 receives optical signals from a router 311 andtransmits the received optical signals to the ROADM 331. The ROADM 331has loopback capability as described to re-direct part of the receivedoptical signals back to the router 311, if the router 311, the Mux/Demux321, and the ROADM 331 are connected correctly, following the same beampath as the incident optical signals. In the fixed-color Mux/Demux 321,each output port (e.g., for de-multiplexed signals) is configured todeliver a spectral component having a given wavelength and but not otherwavelengths.

FIG. 3B shows a schematic of an optical network 302 using a colorlessMux/Demux 322 and a ROADM 332. The ROADM 331 can be, for example,similar to the ROADM discussed above in reference to FIG. 1. TheMux/Demux 322 receives optical signals from a router 312 and transmitsthe received optical signals to the ROADM 332. The ROADM 332 hasloopback capability as described to re-direct part of the receivedoptical signals back to the router 312.

In some implementations, the colorless Mux/Demux 322 can include acyclic arrayed waveguide grating (AWG), which can operate as a staticwavelength router. A cyclic AWG can include a set of input ports and aset of output ports. For example, an N×N cyclic AWG includes N inputports and N output ports. When a comb of N Wavelengths is applied at oneinput port (e.g., a first input port), the wavelengths in the comb aresplit so that each wavelength of the comb is present at a correspondingoutput port. If the same wavelength comb is applied to a different inputport (e.g., a second input port), the wavelengths are split again amongthe output ports, but in a different order. This can ensure that nooutput port experiences a collision of equal wavelengths coming fromdifferent input ports.

Operation of a cyclic AWG AWG Input Port 1 2 3 4 5 6 7 8 9 10 AWG 1 λ1λ2 λ3 λ4 λ5 λ6 λ7 λ8 λ9  λ10 Output 2 λ2 λ3 λ4 λ5 λ6 λ7 λ8 λ9  λ10 λ1Port 3 λ3 λ4 λ5 λ6 λ7 λ8 λ9  λ10 λ1 λ2 4 λ4 λ5 λ6 λ7 λ8 λ9  λ10 λ1 λ2 λ35 λ5 λ6 λ7 λ8 λ9  λ10 λ1 λ2 λ3 λ4 6 λ6 λ7 λ8 λ9  λ10 λ1 λ2 λ3 λ4 λ5 7 λ7λ8 λ9  λ10 λ1 λ2 λ3 λ4 λ5 λ6 8 λ8 λ9  λ10 λ1 λ2 λ3 λ4 λ5 λ6 λ7 9 λ9  λ10λ1 λ2 λ3 λ4 λ5 λ6 λ7 λ8 10  λ10 λ1 λ2 λ3 λ4 λ5 λ6 λ7 λ8 λ9

Table 1 above gives an example for a 10 channel AWG. In practice, thecyclic AWGs can support 40 channels or more. In this example, thewavelength comb includes 10 spectral components λ1 to λ10. If thewavelength comb is delivered to the first input port, the outputwavelengths at the ten output ports are following the order λ1, λ2, . .. , to λ10. If the same wavelength comb is delivered to the second inputport, the output wavelengths at the ten output ports are then followingthe order, λ2, λ3, . . . , λ10 and λ1. The orders of the outputwavelengths when the wavelength comb is delivered into other input portscan be similarly found in Table 1 below.

FIG. 4 illustrates a method 400 of optical channel management using aROADM with loopback capabilities, according to an embodiment. The method400 includes, at 410, receiving a first optical signal from a seconddevice via an input port of a reconfigurable optical add/dropmultiplexer (ROADM). At 420, the first optical signal is transmitted toa first wavelength selective switch (WSS), which converts the firstoptical signal into a second optical signal. At 430, the second opticalsignal is transmitted to a second WSS, which converts the second opticalsignal to a third optical signal. As used herein, the term “convert” mayinclude, for example, actions of shaping the optical signals, switchingthe optical signals to a certain propagation direction, and/oramplifying the optical signals to a defined level. In someimplementations, the second optical signal can be substantiallyidentical to the first optical signal (except, for example, thepropagation direction). In some implementations, the third opticalsignal can be substantially identical to the second optical signal.

The method 400 further includes, at 440, transmitting the third opticalsignal towards the second device via the input port. The second devicecan use the received third optical signal (or the absence of any thirdoptical signal) to evaluate the optical connection between the seconddevice and the ROADM.

In some implementations, the second device includes a router. In someinstances, the second device can deliver the optical signals to theROADM via an intermediary device, such as a switch or a Mux/Demux.

In some implementations, the method 400 further includes amplifying thesecond optical signal before transmitting the second optical signal tothe second WSS. In some embodiments, the second optical signal can beamplified by an erbium doped fiber amplifier. In some embodiments, thesecond optical signal can be amplified by any other appropriateamplifiers.

In some implementations, the method 400 further includes acquiringspectral information of the first optical signal. The spectralinformation can be used to locate the user port that is configured toreceive the second optical signal. In these cases, the second opticalsignal and the spectral information can be sent back to the seconddevice for optical channel management.

In some implementations, the method 400 further includes acquiring firstspectral information of the first optical signal and transmitting aportion of the second optical signal to at least one user port. Thelocation of the user port receiving the second optical signal is thendetermined by the first spectral information. The spectral informationof the second optical signal (referred to as the second spectralinformation) is also acquired. The method 400 further includesprovisioning an optical channel on the user port based at least in parton the first spectral information and the second spectral information.The spectral information in these implementations can be acquired by,directing part of the first optical signal and the second optical signalto an optical channel monitor (OCM).

In some implementations, the method further includes generating a statusrepresenting connection between the second device and the input portbased at least in part on the third optical signal or the absence of thethird optical signal. For example, if no signal is received by thesecond device, then the second device can determine that the seconddevice is incorrectly connected to the ROADM or not connected to theROADM at all. If some signal is received but at the wrong wavelength,then the second device can determine that the cabling between the seconddevice and the ROADM is incorrect. If some signal at the correctwavelength is received but the signal level is low, then the seconddevice can determine that the contact between the second device and theROADM may be compromised by, for example, dust or other contamination.

In some implementations, the method 400 further includes acquiring firstspectral information of the first optical signal and transmitting aportion of the second optical signal to at least one user port in a setof multiple user ports. The second spectral information transmitted toeach user port is acquired. The method 400 further includes locating theuser port that receives the second optical signal based at least in parton the first spectral information and the second spectral information.

In some implementations, the method 400 further includes acquiring firstspectral information of the first optical signal and transmitting aportion of the second optical signal to at least one user port in a setof multiple user ports of the ROADM. The power at each user port is thendetected. In response to detection of optical power at some user ports,the method 400 further includes acquiring respective second spectralinformation transmitted to each user port in those user ports whereoptical power is detected. The user port that receives the secondoptical signal is the located (or identified) based at least in part onthe first spectral information and the second spectral information.

In some implementations, the first optical signal includes multiplefirst test signals output from a colored multiplexer/demultiplexer. Eachfirst test signal has a distinct wavelength. The method further includestransmitting the first test signals to the first WSS to convert thefirst test signal into second test signals. At least one of the secondtest signals is transmitted to a user port. The method further includesreceiving at least some of the second test signals at the second deviceand locating (or identifying) at least one optical path between thesecond device and the user port. The location can be based on thespectral information of the second test signals received at the seconddevice.

In some implementations, the first optical signal includes a firstoutput signal from a colorless multiplexer/demultiplexer, and the methodfurther includes transmitting the first output signal to the first WSSto convert the output signal into a second output signal. At least aportion of the second output signal is transmitted to a user port. Usingthe loopback capability of the ROADM, at least a portion of the secondoutput signal is sent back towards the second device. At least oneoptical path between the second device and the user port is thendetermined (or identified) based on the portion of the second outputsignal (or the absence of any second output signal) received at thesecond device.

In some implementations, the method 400 further includes setting a timerwith a predetermined expiration time. In response to no signal receivedby the router within the predetermined expiration time, the method 400includes generating an error message representing an erroneousconnection between the second device and the input port.

FIGS. 5A and 5B illustrates steps taken on a router in a method 500 oftesting optical channel consistency. In some implementations, the method500 can be performed manually. In some implementations, the method 500can be automated using a command: test interface <interface-name> otnconsistency central-frequency <frequency> [no configure]. In thiscommand, the “interface” is the interface name of the transponder (alsoreferred to as a transceiver, i.e. the combination of transmitter andreceiver) on the router, and “central-frequency” is the frequency valueof the optical signal to use when programming the transponder in THz.

The method 500 starts at 510 and proceeds to 512, where the presence ofthe frequency parameter is determined, i.e., checking if someone hasconfigured manually which frequency shall be chosen. If the frequencyparameter is present, the method 500 proceeds to 530 illustrated in FIG.5B. Otherwise, the method 500 proceeds to 514, where the method 500determines whether the interface (e.g., a transceiver module, such as atransceiver module on the left side of the router 312 shown in FIG. 3B)is assigned a frequency. If so, the method 500 again proceeds to 530.Otherwise, an error message is generated at 520 and the error messageindicates that the interface must have frequency assigned.

At 530, the transponder on the ROADM is tuned to the assigned frequencyif the transponder has an assigned frequency (from 512). If thetransponder does not have an assigned frequency, then the transponder istuned to the supplied frequency, which can be selected from a list ofunused frequencies. In other words, if the transponder has no configuredfrequency, the transponder can pick one frequency (i.e., a suppliedfrequency) that is currently unused and run the connectivity check. Ifsuccessful, the picked frequency is confirmed and then reserved for thattransceiver at 514.

In addition, the trail trace identifier (TTI) is set on test pattern. ATTI is usually used to identify the optical signal from the source tothe destination within the optical network. The TTI can contain anaccess point identifier(s) (API), which are used to specify the source,and a destination access point identifier(s) (DAPI). The APIs containinformation regarding the country of origin, network operator, andadministrative details.

At 532, an optical signal indicating the frequency information andmux-demux type is sent to each candidate ROADM. A timer is set at 534and the router is then set to wait for ROADM to respond at 536. In someimplementations, the timer can be set at about 3 minutes. In some otherembodiments, the timer can be set at about 30 seconds to about 10minutes (e.g., about 30 seconds, about 1 minute, about 2 minutes, about3 minutes, about 5 minutes, or about 10 minutes, including any valuesand sub ranges in between).

At 540, the router checks whether any response is received from anyROADM. If so, the router also checks whether the received response hasan error at 542. The method 500 the proceeds to 550, where theconnection table is updated with identification information of the ROADM(e.g., based on the received response), user port number in the ROADM,and client port number in the Mux/Demux (e.g., see FIG. 3). The timer isthen cancelled at 552.

At 554, the router checks whether automatic configuration is requested.If so, the method proceeds to 560, where the interface on the ROADM isconfigured and an optical channel on the ROADM is also configured. Themethod 500 then proceeds to 580, where the router sends a message to theROADM to request release of loopback (i.e., the ROADM loopbacks signalsto the router). As used herein, configuration can refer to the action inwhich the frequency is now reserved for that transponder. In other wordsthe frequency is removed from the list of available frequencies and putinto the configuration of the transceiver.

FIG. 6 illustrates a method 600 of optical channel consistency testtaken on a ROADM, according to an embodiment. The method 600 starts at610 and the moves to 620, where the ROADM receives an optical signalindicating frequency information and Mux/Demux type information from therouter. The ROADM then checks whether the Mux/Demux is a colorlessMux/Demux at 625. If so, the ROADM tunes the next user port to thereceived frequency at 630. If not, the ROADM determines, at 640, theuser port from the received frequency using, for example, an opticalchannel monitor (OCM).

After either 630 or 640, the method 600 determines whether any power isdetected at the user port, at 645. If power is detected, an opticalswitch in the ROADM is set to source the requested user port (i.e.,where power is detected), at 650. The ROADM also checks the OCM forfrequency presence at 660 and reports the frequency state to the routerat 670. The sourcing step can be illustrated with reference to FIG. 1.The apparatus in FIG. 1 includes ports 110 a to 110 b labeled U1 to U20,respectively. Assuming the spectral analyzer 155 a detects some increaseof power, the spectral analyzer then informs the OCM 150. Then the OCM150 tunes its monitoring capability to identify and/or locate thecorresponding interface (i.e., 110 a in this case). During that time,none of the other 19 remaining interfaces is monitored.

If no power is detected at 645 (or after 670), the method 600 proceedsto 672, where the ROADM again checks the type of the Mux/Demux. Ifcolorless Mux/Demux is used, the ROADM determines whether more userports are to be checked at 674. If more user ports are to be checked,the method 600 proceeds back to 630. Otherwise, the method 600 ends at680. If at 672, the ROADM determines that a fixed-color Mux/Demux isused, the method 600 directly proceeds to the end at 680.

At least three scenarios are possible in optical channel consistent testdescribed above. In the first scenario, the router, the Mux/Demux, andthe ROADM are connected correctly. More specifically, the router isconnected to the correct client port on the Mux/Demux, and the Mux/Demuxline port is connected to the correct ROADM. In this case, expectedoptical signals are looped back from the ROADM and received by therouter.

For example, a user may intend to connect the router to Mux/Demux clientport 95 and connect Mux/Demux line port to port U0 on a ROADM. And therouter, the Mux/Demux, and the ROADM are indeed connected as intended.In this case, an example of optical consistency test on the router canbe described as follows. First, a frequency of about 196.1 THz can beset on the router (e.g., et-7/1/0) and a topology table can include thisfrequency. A topology table can be, for example, a list of nodesdescribing for each connection for which wavelengths are already in use.This list can be constructed using communication channels and usuallydoesn't need a test pattern.

Then the TTI is set to test pattern (e.g., using command “Testinget-7/1/0 with frequency 196.1 THz”). The test then proceeds to find allROADMs that do not have frequency 196.1 configured. The router thensends a message to all ROADMs in the ROADM list including“frequency=196.1 and fixed-color mux-demux type.” A three-minute timeris set to wait for responses.

The test then proceeds to process the response from each ROADMs. Theresponse may contain the following information: id=fpc 101 (i.e., ROADMID), mux-demux client port=C95, SD user port=U0. The test then cariesout TTIRx=“Testing et-7/1/0 with frequency 196.1 THz” and checks biterrors. At this step, once it is clear that the frequency is available,the two user ports at the two ends (e.g., on the ROADM and themux/demux) are connected and checked for bit-errors.

If this step passes, the topology table is filled with informationreceived from the ROADM. Timer is then cancelled. The router then sendsa message to the ROADM indicating that the test is complete. Ifautomatic configuration is selected, the ROADM is set at 196.1 THz. Thechannel configuration is also sent to the ROADM with frequency at 196.1THz and ROADM User Port=U0.

On the ROADM, the test can be described as follows. The ROADM firstreceives the message from the router, including the information:frequency=196.1, Mux/Demux type=fixed-color. The ROADM then translatesthe frequency (i.e., 196.1 THz) to Mux/Demux client port (i.e., C96) andstarts a loop over user ports. If no power is present on the port beinginterrogated, the test continues to check other user ports. Otherwise,the ROADM sets the optical switch to direct User Port 0 and acquirespectral information from the OCM. If the frequency at 196.1 THz ispresent, the test passes and the ROADM sets loopback for frequency 196.1THz on User Port 0. After the round finishes, the ROADM receives amessage from the router indicating that the test is complete. Theloopback can then be terminated. In some instances, auto-configurationis selected, and the ROADM receives a message from the router includinga configuration request: frequency=196.1, User Port=0. In this case, theROADM provisions the channel at 196.1 THz on port U0.

In the second scenario, the router is connected to the wrong Mux/Demuxclient port but the Mux/Demux line port is connected by an optical fiberto the correct ROADM. In this case, the router usually sees errorindication from the ROADM.

For example, the user may intend to connect the router (e.g., et-7/1/0)to Mux/Demux client port 95 and connect Mux/Demux line port to port U1on the ROADM. The actual connection, however, is that the router isconnected to Mux/Demux client port 94 (incorrect connection) and theMux/Demux line port is connected by an optical fiber to port U1 on theROADM (correct connection).

In this case, an example of optical consistency test on the router canbe described as follows. First, a user sets frequency on the router tobe 196.1 THz and sets this frequency in the topology table to 196.1 THz.Then the user can set TTI to “Testing et-7/1/0 with frequency 196.1 THz”and find all ROADMs that do not have frequency 196.1 THz configured. Therouter also sends a message to all ROADMs including: frequency 196.1 THzand fixed-color mux-demux type. A 3 minutes timer is set to wait forresponses. In this second scenario, the timer would expire. The testthen carries out TTIRx=“Testing et-7/1/0 with frequency 196.1 THz” whichwould fail. The router then updates topology table with “Test failed: Nosignal detected” and sends a message to ROADMs indicating that the testis complete.

On the ROADM, the test can be described as follows. The ROADM receivesthe message from the router, including the frequency information and thetype of the Mux/Demux. The ROADM translates the frequency (196.1 THz) toMux/Demux client port (i.e., C95) and starts the loop over user ports.For a given user port, if no power is detected, the ROADM checks nextuser port. If power is detected, the ROADM sets the optical switch todirect current User Port and acquire spectral information from the OCM.The ROADM then tests the presence of 196.1 THz but this test would failin this second scenario. The ROADM moves to Next Port and loops over allUser Ports until the Test Complete signal is received from the router.At this step, the ROADM stops looping User Ports.

In the third scenario, the router is connected to the correct Mux/Demuxclient port but the Mux/Demux line port is connected to the wrong ROADM.In this case, the router receives unexpected information from theloopback of the ROADM.

For example, a user may intend to connect the router to Mux/Demux clientport 95 and connect Mux/Demux line port to port U1 on the ROADM (e.g.,fpc 101). The actual connection is, however, that the router isconnected by an optical fiber to Mux/Demux client port 95 (correctconnection) and the Mux/Demux line port is connected to port U1 on theROADM fpc 102 (wrong connection).

In this case, an example of optical consistency test on the router canbe described as follows. First, a user sets frequency on et-7/1/0 to196.1 THz and sets this frequency in the topology table to 196.1 THz.Then the user can set TTI to “Testing et-7/1/0 with frequency 196.1 THz”and the router can find all ROADMs that do not have frequency 196.1 THzconfigured. The router then sends a message to all ROADMs, including:frequency=196.1 THz and fixed-color mux-demux type. A 3 minute timer isset to wait for responses.

The router then processes responses from ROADMs including: ROADM id=fpc102, Mux/Demux client port=C95, and SD user port=U1. The router thentests for TTIRx=“Testing fpc 7 with frequency 196.1 THz” and tests forbit errors. If these two steps pass, the router fills in otn-connectiontable with information received from the ROADM(s). This otn-connectiontable is created at each node. Accordingly, each node “knows” (or hasinformation on) which end points are connected at which frequency andthrough which ROADM. The timer is cancelled and the router sends amessage to the ROADM(s) indicating that the test is complete. In someembodiments, the automatic configuration is selected and the topologystatus is not equal to “Mismatch.” The router then sets frequency in fpc7 configuration to 196.1 THz and sends configuration to ROADM including:frequency=196.1, ROADM User Port=U1.

On the ROADM, the test can be described as follows. The ROADM receivesthe message from the router including the frequency information and thetype of the Mux/Demux. The ROADM also translates frequency (i.e., 196.1THz) to Mux/Demux client port (i.e., C95) and starts a loop over userports. For a given user port, if no power detected, the ROADM continuesthe loop. If power is detected, the ROADM sets the optical switch todirect User Port 1 and acquires spectral information from the OCM. TheROADM also tests for the presence of the frequency 196.1 THz. This stepwould pass in this third scenario. The ROADM then sets loopback forfrequency 196.1 THz on User Port 1 and receives a message from therouter that the test is complete. The ROADM then removes the loopback.In some instances, the auto-configuration mode is selected and the ROADMreceives the message from the router including a configuration request:frequency=196.1 THz, User Port=1. The ROADM then provisions channel(196.1 THz) on port U1.

In the event that the optical channel consistency test fails, an opticalchannel sweep test can be performed to find user port on the ROADM isconnected to the router. This test is only performed for ROADM userports that are connected to fixed-color Mux/Demux, but not whenconnected to a colorless Mux/Demux. This is because for colorlessMux/Demux, the optical channel consistency check is itself a sweep testwhere the sweep occurs on the ROADM. For this test the sweep occurs onthe router. For ROADM user ports that have fixed-color Mux/Demux, thistest can cycle through the available wavelengths on the ROADMs to seewhich client port of the Mux/Demux the router is connected to.

FIG. 7 illustrates a method 700 of optical channel sweep test performedon a router, according to an embodiment. The method 700 starts at 705and proceeds to build a frequency table at 710. The frequency table caninclude all unused frequencies for all ROADMs. Over the frequency table,the router selects next free frequency at 715 and tunes the transponderon the router to the selected frequency at 720. The router also sets theTTI to the test pattern at this point.

At 725, the router sends the frequency information and the type of theMux/Demux to each candidate ROADM. A 3-minute timer is set at 730 towait for responses at 735. At 740, the router determines whether anyresponse is received from the ROADM and further determines whether thereceived response is error free at 742. At 745, the router updates theconnection table, followed by cancelling the timer at 748.

After 748, or after the expiration of the timer at 750, the method 700then proceeds to 760, where the router sends a message to the ROADMrequesting the release of loopback. If the supplied frequency is foundat 765, the method 700 stops at 780. Otherwise, the router determineswhether more frequencies are to be checked at 770. If there are morefree frequencies, the method 700 moves to 715 and start another round ofsweep test. If there is no more free frequency, the method 700 ends at780.

FIG. 8 illustrates a method 800 of optical channel sweep test performedon a ROADM, according to embodiments. The method 800 starts at 805 andthe ROADM receives a signal indicating the frequency information and thetype of the Mux/Demux from the router at 810. The ROADM then selectsnext user port at 820. At 825, the ROADM determines whether colorlessMux/Demux is used. If so, the ROADM tunes the Mux/Demux port to thereceived frequency. If a fixed-color Mux/Demux is used, the method movesto 830, where the ROADM determines the Mux/Demux port from the receivedfrequency.

The ROADM then detects whether any power is detected for the selecteduser port at 835. If power is detected, the ROADM sets the opticalswitch to source the selected user port at 840 and also checks the OCMfor frequency presence at 850. The ROADM also reports the frequencystate to the router at 860. After 860, or in the event that no power isdetected at 835, the method proceeds to 862, where the ROADM determinesagain the type of Mux/Demux.

If the Mux/Demux is colorless, the ROADM checks whether more Mux/Demuxports are to be checked at 864. If more Mux/Demux ports are to bechecked, the method proceeds to 870 and initiate another round of sweeptest. If, however, there is no more Mux/Demux port to check, the methodproceed to 866, where the ROADM checks whether there are more user portsto check. If so, the method 800 moves back to 820 to initiate anotherround of sweep test. If there is no more user port to check, the methodends at 880.

In addition to the optical channel consistency test and the opticalchannel sweep test, an optical channel discovery can also be performedto determine which router is connected to which port at which ROADM. Inthis test, a “Master Router” can control the execution of the test. The“Master Router” assigns the frequency (also referred to as pilotfrequency). The test is performed to all transponders on all routers andincludes all ROADMs. The optical channel consistency test describedabove can also be performed one by one.

In some implementations, the optical channel discovery test can beperformed automatically using, for example, a processor. In someimplementations, the optical channel discovery test can be performedmanually. In automatic operation, the optical channel discovery startsupon plug-in of a pluggable ROADM. In this operation, the routerprograms a pilot frequency on the router and all ROADMs. The ROADMmonitors all unconfigured user ports. Upon reception of power, aloopback of pilot frequency is set up. The router port also checksquality of connection and assigns frequency.

FIG. 9 illustrates a method 900 of optical channel discovery performedon a router, according to embodiments. The method 900 starts at 905 andmoves to 910, where the router builds a table including all freefrequencies. The router then selects next free frequency (referred to aspilot frequency) at 915 and tunes the transponder to the pilot frequencyat 920. The router also sets the TTI to test pattern at 920. A timer isset at 930 to wait for responses at 935.

At 940, the router checks whether any signal is received from loopbackwithin the preset time duration on the timer. The router also updatesthe connection table based on received loopback at 950 and cancels thetimer at 955. Alternatively, the router may not receive any signal fromthe loopback in ROADMs and the timer expires at 960. After either 960 or955, the method proceeds to 970, where the router checks whether thereis more free frequency to run the test. If so, the method 900 returns to915 and initiates another round of channel discovery. If there is nomore free frequency, the method 900 ends at 980.

FIG. 10 illustrates a method 1000 of optical channel discovery performedon a ROADM, according to an embodiment. The method 1000 starts at 1005and includes receiving a message from the router including the pilotfrequency information at 1110. At 1120, the ROADM detect power at oneuser port (i.e., Ux). If power is detected (or above a threshold), theROADM sets the optical switch to loopback the user port and tests forthe presence of the pilot frequency, at 1030. The ROADM also reports theuser port information to the router at 1050. The method 1000 then endsat 1060. In the event that no power is detected at the user port at1020, the method moves to 1040, where the ROADM either removes theloopback or waits forever. As described above, the ROADM operates in anidle mode (also referred to as a monitoring mode) until it detects somepower change at monitoring points, such as 155 a shown in FIG. 1. Assoon as a power change is detected the discovery procedure is invoked.

While various embodiments have been described and illustrated herein, avariety of other means and/or structures for performing the functionand/or obtaining the results and/or one or more of the advantagesdescribed herein, and each of such variations and/or modifications arepossible. More generally, all parameters, dimensions, materials, andconfigurations described herein are meant to be examples and that theactual parameters, dimensions, materials, and/or configurations willdepend upon the specific application or applications for which thedisclosure is used. It is to be understood that the foregoingembodiments are presented by way of example only and that otherembodiments may be practiced otherwise than as specifically describedand claimed. Embodiments of the present disclosure are directed to eachindividual feature, system, article, material, kit, and/or methoddescribed herein. In addition, any combination of two or more suchfeatures, systems, articles, materials, kits, and/or methods, if suchfeatures, systems, articles, materials, kits, and/or methods are notmutually inconsistent, is included within the inventive scope of thepresent disclosure.

Also, various inventive concepts may be embodied as one or more methods,of which an example has been provided. The acts performed as part of themethod may be ordered in any suitable way. Accordingly, embodiments maybe constructed in which acts are performed in an order different thanillustrated, which may include performing some acts simultaneously, eventhough shown as sequential acts in illustrative embodiments.

All definitions, as defined and used herein, should be understood tocontrol over dictionary definitions, definitions in documentsincorporated by reference, and/or ordinary meanings of the definedterms.

As used herein, a “module” can be, for example, any assembly and/or setof operatively-coupled electrical components associated with performinga specific function, and can include, for example, a memory, aprocessor, electrical traces, optical connectors, software (stored andexecuting in hardware) and/or the like.

The indefinite articles “a” and “an,” as used herein in thespecification and in the claims, unless clearly indicated to thecontrary, should be understood to mean “at least one.”

The phrase “and/or,” as used herein in the specification and in theclaims, should be understood to mean “either or both” of the elements soconjoined, i.e., elements that are conjunctively present in some casesand disjunctively present in other cases. Multiple elements listed with“and/or” should be construed in the same fashion, i.e., “one or more” ofthe elements so conjoined. Other elements may optionally be presentother than the elements specifically identified by the “and/or” clause,whether related or unrelated to those elements specifically identified.Thus, as a non-limiting example, a reference to “A and/or B”, when usedin conjunction with open-ended language such as “comprising” can refer,in one embodiment, to A only (optionally including elements other thanB); in another embodiment, to B only (optionally including elementsother than A); in yet another embodiment, to both A and B (optionallyincluding other elements); etc.

As used herein in the specification and in the claims, “or” should beunderstood to have the same meaning as “and/or” as defined above. Forexample, when separating items in a list, “or” or “and/or” shall beinterpreted as being inclusive, i.e., the inclusion of at least one, butalso including more than one, of a number or list of elements, and,optionally, additional unlisted items. Only terms clearly indicated tothe contrary, such as “only one of” or “exactly one of” or, when used inthe claims, “consisting of,” will refer to the inclusion of exactly oneelement of a number or list of elements. In general, the term “or” asused herein shall only be interpreted as indicating exclusivealternatives (i.e. “one or the other but not both”) when preceded byterms of exclusivity, such as “either,” “one of” “only one of” or“exactly one of” “Consisting essentially of,” when used in the claims,shall have its ordinary meaning as used in the field of patent law.

As used herein in the specification and in the claims, the phrase “atleast one,” in reference to a list of one or more elements, should beunderstood to mean at least one element selected from any one or more ofthe elements in the list of elements, but not necessarily including atleast one of each and every element specifically listed within the listof elements and not excluding any combinations of elements in the listof elements. This definition also allows that elements may optionally bepresent other than the elements specifically identified within the listof elements to which the phrase “at least one” refers, whether relatedor unrelated to those elements specifically identified. Thus, as anon-limiting example, “at least one of A and B” (or, equivalently, “atleast one of A or B,” or, equivalently “at least one of A and/or B”) canrefer, in one embodiment, to at least one, optionally including morethan one, A, with no B present (and optionally including elements otherthan B); in another embodiment, to at least one, optionally includingmore than one, B, with no A present (and optionally including elementsother than A); in yet another embodiment, to at least one, optionallyincluding more than one, A, and at least one, optionally including morethan one, B (and optionally including other elements); etc.

In the claims, as well as in the specification above, all transitionalphrases such as “comprising,” “including,” “carrying,” “having,”“containing,” “involving,” “holding,” “composed of,” and the like are tobe understood to be open-ended, i.e., to mean including but not limitedto. Only the transitional phrases “consisting of” and “consistingessentially of” shall be closed or semi-closed transitional phrases,respectively, as set forth in the United States Patent Office Manual ofPatent Examining Procedures, Section 2111.03.

What is claimed is:
 1. A method, comprising: acquiring, via a firstspectral analyzer, first spectral information of a first optical signalof a device; receiving, via a user port, a second optical signalconverted from the first optical signal; acquiring, via a secondspectral analyzer, second spectral information of the second opticalsignal; receiving, at an optical channel monitor (OCM), the firstspectral information from the first spectral analyzer and the secondspectral information from the second spectral analyzer; locating theuser port based at least in part on the received first spectralinformation; and transmitting the second spectral information to thedevice.
 2. The method of claim 1, wherein locating the user portincludes locating the user port based at least in part on the secondspectral information.
 3. The method of claim 1, further comprisingacquiring, via the second spectral analyzer, power information on theuser port.
 4. The method of claim 1, wherein the second optical signalis converted from the first optical signal to the second optical signalusing a wavelength selective switch (WSS).
 5. The method of claim 1,wherein the first optical signal includes a plurality of test signalsoutput from a colored multiplexer/demultiplexer, each test signal fromthe plurality of test signals having a distinct wavelength.
 6. Themethod of claim 1, wherein the first optical signal includes an outputsignal from a colorless multiplexer/demultiplexer.
 7. The method ofclaim 1, further comprising: setting a timer with a predeterminedexpiration time; and in response to no signal being received within thepredetermined expiration time, generating an error message representingan erroneous connection between the device and an input port.
 8. Themethod of claim 1, further comprising: provisioning an optical channelon the user port based at least in part on the first spectralinformation and the second spectral information.
 9. The method of claim1, further comprising amplifying the second optical signal using anoptical amplifier.
 10. An apparatus, comprising: an input port toreceive a first optical signal from a device; a wavelength selectiveswitch (WSS), in optical communication with the input port, to convertthe first optical signal into a second optical signal; a loopback, inoptical communication with the WSS, to transmit the second opticalsignal to the device; and a transponder operatively coupled to the inputport and configured to generate an error message representing anerroneous connection between the device and the input port in responseto no signal being received by the device.
 11. The apparatus of claim10, further comprising: a timer configured to count a predeterminedexpiration time, the timer being operatively coupled to the transponder,the transponder configured to generate the error message when no signalbeing received by the device within the predetermined expiration time.12. The apparatus of claim 10, wherein the device includes a router. 13.The apparatus of claim 10, wherein the first optical signal includes aplurality of test signals output from a coloredmultiplexer/demultiplexer, each test signal from the plurality of testsignals having a distinct wavelength.
 14. The apparatus of claim 10,wherein the first optical signal includes an output signal from acolorless multiplexer/demultiplexer.
 15. The apparatus of claim 10,further comprising: a first spectral analyzer configured to acquirefirst spectral information of the first optical signal of the device;and a second spectral analyzer configured to acquire second spectralinformation of the second optical signal.
 16. An apparatus, comprising:a first spectral analyzer operatively coupled to an input portconfigured to receive a first optical signal from a device, the firstspectral analyzer configured to acquire first spectral information ofthe first optical signal; a second spectral analyzer, operativelycoupled to a user port configured to receive a second optical signalconverted from the first optical signal, the second spectral analyzerconfigured to acquire second spectral information of the second opticalsignal, the user port being operatively coupled to the input port; andan optical channel monitor (OCM), operatively coupled to the firstspectral analyzer and the second spectral analyzer, configured to:receive the first spectral information from the first spectral analyzer;locate the user port based at least in part on the first spectralinformation; receive the second spectral information from the secondspectral analyzer; and transmit the second spectral information to thedevice.
 17. The apparatus of claim 16, wherein the OCM is furtherconfigured to: locate the user port based at least in part on the secondspectral information.
 18. The apparatus of claim 16, wherein the secondspectral analyzer is further configured to acquire power information onthe user port.
 19. The apparatus of claim 16, further comprising awavelength selective switch (WSS), in optical communication with theinput port, to convert the first optical signal into the second opticalsignal.
 20. The apparatus of claim 16, wherein the first optical signalincludes a plurality of test signals output from a coloredmultiplexer/demultiplexer, each test signal from the plurality of testsignals having a distinct wavelength.